Preparation and sound absorption properties of multi-layer composites formed by waste polyphenylene sulfide filters

Composite materials with multi-layer structure were prepared by combining polyurethane film and waste polyphenylene sulfide filters by hot melting, which could be used as sound-absorbing materials to contribute to the noise control and reutilization of industrial waste. The structure, mechanical property, pore size distribution and stability of waste polyphenylene sulfide filters were investigated and could directly affect the quality of recycled products. The effects of layer numbers, layering sequence and polyurethane film thickness on sound absorption and insulation properties were also analyzed using an impedance tube absorption test system. The results showed that multi-layer materials had a better sound absorption effect than single-layer polyphenylene sulfide filters at low frequency. The sound absorption coefficients of the single-layer sample was only 0.081 at 1000 Hz, while the sound absorption coefficients of the five-layer sample could reach 0.26. The sound absorption properties of multi-layer materials were slightly affected by layering sequence, but polyurethane film thickness had a significant effect on sound absorption properties. The α of the SUS1 and USU1 samples were 0.151 and 0.170, while the α of the SUS3 and USU3 samples were only 0.076 and 0.056, respectively. Meanwhile, the sound insulation properties of multi-layer materials could be significantly influenced by the polyurethane film position. The sound transmission loss of the SUSUSU3 sample was just 32.83 dB, whereas that of the USUSU3 sample could reach 47.94 dB. Moreover, when polyurethane film was located on the sound facing side of multi-layer materials, the increase in polyurethane film thickness could cause the average sound reduction index of the USUSU sample to increase from 28.76 dB to 47.94 dB.